his book on hybrid electric vehicles brings out six chapters on some of the research activities through the wide range of current issues on hybrid electric vehicles. The first section deals with two interesting applications of HEVs, namely, urban buses and heavy duty working machines. The second one groups papers related to the optimization of the electricity flows in a hybrid electric vehicle, starting from the optimization of recharge in PHEVs through advance storage systems, new motor technologies, and integrated starter-alternator technologies. A comprehensive analysis of the technologies used in HEVs is beyond the aim of the book. However, the content of this volume can be useful to scientists and students to broaden their knowledge of technologies and application of hybrid electric vehicles.